In U.S. Pat. No. 4,534,174 there is disclosed an apparatus and method for handling geothermal brine from geothermal sources in such a way that the energy content is extracted from the geothermal brine and used to perform useful work.
In the patent, there is disclosed the method in which brine from a geothermal well is pre-flashed to separate the liquid and vapor fractions of the brine, the vapor fraction including steam and non-condensible gases. The vapor fraction is sent to a direct contact reboiler where the steam is used to heat a relatively cool condensate flowing through the reboiler, and the non-condensible gases are cooled and separated from the steam.
Heated condensate flowing out of the direct contact reboiler can be flashed in a first flash chamber to provide steam to drive a high pressure turbine. Condensate from the first flash chamber is directed to a second flash chamber to provide steam to drive a low pressure turbine. Then the condensate from the second flash chamber is recirculated back to the direct contact reboiler to provide a substantially closed system.
It has been found that the system can be made more efficient by additional handling of the condensate from the first flash chamber. The present invention is therefore based upon this concept.